The present invention generally relates to a vapor vent valve used in combination with a fuel tank employed in an automotive vehicle and, more particularly, to a vapor vent valve capable of being welded directly onto a polymeric fuel tank employed in an automotive vehicle.
Fuel tanks employed in automotive vehicles require means for keeping the internal pressure within the fuel tanks substantially in equilibrium with atmosphere. Various conditions, such as extremes of heat and cold will affect the internal pressure within the internal chamber of a fuel tank. Likewise, as fuel is withdrawn from a tank, the internal pressure therein will also change. Vent/relief mechanisms have been employed in the prior art in order to keep the internal pressure within a tank substantially at equilibrium with atmosphere. Such a vent/valve mechanism may comprise a carbon canister where vapors from the tank are collected and eventually delivered to the engine for combustion.
The vapor vent valves employed in the vent/relief mechanisms normally include means for preventing fuel from leaking out of a tank if, for example, the vehicle travels along a very steep incline causing fuel to enter into the vapor vent valve. The means employed for preventing fuel leakage may comprise a known internal shut-off mechanism included within the vapor vent valve.
It is also known in the prior art to use fuel tanks made from polymeric materials, such as polyethylene, in automotive vehicles. Such fuel tanks are advantageous because they resist corrosion and can be easily formed having various shapes and sizes, thus permitting flexibility in their design. Further, since polymeric fuel tanks are light weight, they make the vehicles in which they are employed more fuel efficient and economical to operate
Arrangements for mounting vapor vent valves onto fuel tanks are known in the prior art. One such arrangement is disclosed in U.S. Pat. No. 4,753,262, wherein an outer plastic casing of the valve is formed with external threads for threadedly connecting the valve within an opening in a fuel tank. Such a connection requires the threads to be molded within the tank wall.